Orthodontic spring



FIG. 1 is a front perspective view of an orthodontic spring showing my new design.

FIG. 2 is front elevational view thereof.

FIG. 3 is a right side elevational view thereof.

FIG. 4 is a rear elevational view thereof.

FIG. 5 is a left side elevational view thereof.

FIG. 6 is a top plan view thereof; and,

FIG. 7 is a bottom plan view thereof. 

The ornamental design for an orthodontic spring, as shown and described. 